It is known that scientific experiments on laboratory animals are an essential step towards the clinical use of biomedical devices, especially bioelectronic devices, and that the installation of experimental bioelectronic devices in laboratory animals is constantly growing.
There are also already known experimental protocols, e.g. in the treatment of epilepsy, based on the implant of systems for the acquisition and monitoring of brain bioelectric signals in human beings.
Charging of these bioelectronic devices may be performed by using appropriate cables or in a wireless mode by electromagnetic induction. The latter mode is preferred because the use of cables is a source of infection for laboratory animals as well as for patients, which cannot be eliminated but removing the implanted device, thus resulting in the interruption of experimental activities or therapies. The elimination of supply cables, which are external bodies having a not negligible size, also prevents laboratory animals and patients from experiencing behavioral problems during the experimental activity or therapy.
In order to perform wireless charging it is necessary to magnetically couple a winding of a power supply device, such as an inductive coupler, with a corresponding winding of a power supply circuit associated with the implanted bioelectronic device. To this aim the two windings must be aligned, which requires to hold the laboratory animal or the patient still for the whole time of the experimental activity and/or the complete charging of a rechargeable battery of the bioelectronic implanted device. This situation can be easily managed in the case of a human being thanks to the cooperation of the patient, but in the case of a laboratory animal it is necessary to resort to holding means or even to anesthesia, with serious ethical and organizational problems.
In the specific case of laboratory animals, confinement cages have been developed that are provided with a plurality of windings arranged below the floor on which a laboratory animal can move. The windings can generate a plurality of magnetic fields which are mutually parallel and directed along a vertical axis, whereby the laboratory animal housed in the cage may freely move between the parallel magnetic fields and the power supply circuit of the implanted bioelectronic device is substantially always coupled with at least one of them, so that it may be powered independently of the position of the laboratory animal within the cage.
There are also known power supply systems associated with cages for laboratory animals in which a cage is fully inserted in a winding capable of generating a magnetic field, for example parallel to its axis.
These solutions are very effective in the case of four-legged laboratory animals, such as mice, in which bioelectronic devices can be implanted in a position substantially parallel to the floor, e.g. in the abdomen, but they have proved totally unsuitable for the power supplying bioelectronic to devices implanted in laboratory animals such as monkeys, which have a much greater mobility and continuously move with great agility in the whole available space, e.g. by climbing on the grates forming walls and ceiling of a cage.
A similar but more serious problem arises with patients with implanted bioelectronic devices remotely supplied such as the device disclosed in the patent publication WO 2012/143850 A1 in the applicant's name. A patient in fact cannot be confined in a cage and must be accommodated on a bed or chair for the time necessary to recharge the batteries of the implanted device, which is generally carried out by way of power supply devices comprising windings placed directly in contact with the patient's body in the area where the bioelectronic device is implanted. This condition is poorly tolerated by patients because it requires them to remain substantially still for a relatively long time.